Orthogonal Frequency Division Multiplexing (OFDM) based networks use a multi-carrier transmission technique and are foreseen to be used as access technology in the fourth generation of wireless/mobile communication networks thanks to their ability especially in combination with MIMO antenna technology to reach very high bit rates. OFDM offers a sensible alternative for high-speed mobile applications, and thus represents an important step for next generation mobile radio systems or for a 4th generation air interface to be defined in 3G LTE and 802.16m.
In multi-carrier systems as OFDM transmission system, the transmitted data is split into a number of parallel data streams, each one used to modulate a separate sub-carrier. In other words, the broadband radio channel is subdivided into a plurality of narrow-band subchannels or sub-carriers being independently modulated with e.g. QPSK, 16 QAM, 64 QAM or higher modulation order allowing higher data rate per sub-carrier. The subchannels allocation to a user consists either in consecutive subchannels allocation in a part of the frequency domain of the system also called frequency selective allocation or in single subchannels spread over the entire frequency band of the system called frequency diverse allocation or PUSC in the context of WIMAX.
In such OFDM systems, the sub-carrier frequencies can be allocated to a user channel on a short term basis (e.g. all 2 ms) as well the modulation order per sub-carrier defining a transmission channel for each user should be updated on the same short term basis.
There are different ways to increase the overall throughput of the system.
Firstly, an efficient sub-carrier/modulation allocation should be performed to the different users, i.e when the best appropriate sub-carriers are identified for a user, the optimal modulation to be used on these sub-carriers should be appropriately selected. The higher modulation orders can only be used if the signal to noise ratio (SNR) at the receiver is high enough to allow the demodulation. Secondly, MIMO techniques increase the throughput by providing for 2 or 4 transmit/receive antennas which can operate in parallel.
In all these prior art systems, the decoding at the receiver is based on the fact that the users are using different resources in time, frequency and or code, so that the decoder at the receiver first apply the decoding in knowledge of the resource used by the different users.
A particular object of the present invention is to provide a method for receiving and decoding reliably signals which provide for a further increase of the throughput in a wireless communication system.
Another object of the invention is to provide a corresponding receiver.